1. Technical Field
The present invention relates to a method and apparatus for an effective multi-cell interference control service, and more particularly, to a method and apparatus for a multi-cell interference control service, to make it possible for users located at a cell boundary to dynamically select a suitable interference control technique by monitoring interference information collected by user terminals and network conditions of a serving base station and adjacent base stations to solve co-channel interference by adjacent cell users.
2. Discussion of Related Art
When a user of a wireless terminal is located at a cell/sector boundary, a signal quality of the user's terminal seriously deteriorates by co-channel interference. The conventional art to solve the aforementioned problem has used the techniques, such as power control, user-specific beamforming, soft handover, and frequency re-use among others. However, as a transmission rate becomes high and an available frequency band becomes broad, a service cell radius becomes considerably small and frequent handover is accompanied.
To improve the service cell radius, the next-generation mobile communication standards positively propose the use of a relay. Further, under the conditions where the backhaul capacity between adjacent cells is secured, there are presented the technologies related to inter-cell interference coordination (ICIC), whereby users in a cell-outer area cooperatively and actively solve inter-cell interference (ICI). The ICIC technology is importantly regarded in the orthogonal frequency division multiple access (OFDMA) mode. The ICIC technology is included in the current 802.16 PHY standards and makes positive contributions to the 802.16m TG in relation to the network multiple input multiple output (MIMO) technology.
Furthermore, the ICIC technology has advantages several times those of the inter-cell scheduling technique and the joint power control technique. It also solves efficiency deterioration caused by the relativity between antennas in existing MIMO systems, by using a macro virtual multi-antenna at a distance territorially. In the macro multi-antenna environment among base stations, research is actively conducted regarding the technologies, such as distributed power control (DPC), joint zero forcing (Joint ZF), joint minimum mean square error (Joint MMSE), distributed space-time block code (STBC), joint beamforming, preceding matrix index (PMI) coordination and the like.
However, the aforementioned technologies are based on the precondition: the feedback of a circuit switching (CS) call from a terminal and an internet protocol multimedia subsystem (IMS) session, i.e., “combined CS call and IMS session (CSI)”. Therefore, these technologies have drawbacks in that backhaul traffic occurs when a serving base station (SBS) receiving the transmitted feedback exchanges channel information with adjacent cells.
To solve the problem in that the backhaul traffic occurs in the macro multi-antenna environment, research has started in a limited backhaul capacity environment. In an uplink, research on the inter-base station collaboration interference cancellation is in progress. This research is to accompany the inter-base station channel state information (CSI) sharing and to reduce the inter-base station channel information sharing, by distributed decoding or the like which uses the Joint MMSE or the BCJR algorithm applying successive interference cancellation (SIC).
In an indoor femto cell which is commercialized, it is easy to share the inter-base station channel information due to low backhaul latency. Accordingly, an inter-base station collaboration technique can be applied to the indoor femto cell. In this regard, research needs to be conducted to develop the inter-base station collaboration technology depending on the backhaul latency, and the inter-base station collaboration technology of a flexible cluster size based on level coordination considering the inter-adjacent base station backhaul latency or the like.